The present invention relates to a compensation scheme applied to an electronic apparatus, and more particularly, to an electronic apparatus compensated through monitoring at least a non-temperature factor indicative of frequency drift occurrence of a reference clock and related method thereof.
In general, a reference clock is required for an electronic apparatus to operate normally. Taking the receiver design of a global navigation satellite system (GNSS), such as a global positioning system (GPS), as an example, the GPS receiver includes a GPS IC for processing radio-frequency signals (i.e., satellite signals) and base-band signals for computing the position information and an oscillator acting as a reference clock source with high frequency accuracy. As the positioning performance of the GPS receiver greatly depends on the frequency accuracy of the oscillator, it is desired to make the oscillating signal generated from the oscillator as stable as possible. A temperature compensated crystal oscillator (TCXO) is commonly implemented as the needed reference clock source because a compensation loop is implemented to sense ambient temperature variation by using a temperature sensor and then compensate the oscillating frequency according to the temperature related data given by the temperature sensor. However, in addition to the ambient temperature variation, the oscillator is also influenced by other factors, such as acceleration, unstable power supply, unstable load, and/or change of the operating state. That is, the oscillating signal generated by the temperature compensated crystal oscillator has a frequency drift when one of the non-temperature factors is present. Consequently, the performance of the GPS receiver is degraded as the conventional temperature compensation loop fails to cope with the frequency drift caused by any of the non-temperature factors mentioned above. Herein, the frequency drift includes continuous variation and abrupt jump of frequency.